UMTS系統廣播群播服務之研究

A Study on UMTS Multimedia Broadcasting Multicasting Service

賴彥丞(Yen-Cheng Lai)

指導教授 ： 林風

國立臺灣大學/電機資訊學院/資訊工程學研究所/博士(2008年)

https://doi.org/10.6342/NTU.2008.02375

摘要

在網際網路上，群播技術已被廣泛運用來傳送多媒體內容。近年來，行動通訊網路已經和網際網路成功整合。為了將網際網路上的多媒體服務提供給行動裝置存取，第三代行動通訊網路組織（Third Generation Partnership Project；3GPP）提出了多媒體廣播群播服務（Multimedia Broadcast Multicast Service；MBMS）之相關規範，透過通用行動通訊服務（Universal Mobile Telecommunications System；UMTS）網路將多媒體內容群播給行動裝置。由於多媒體廣播群播服務之相關標準仍持續制定當中，為了提供更好的服務品質與效能之考量，標準所提出的機制仍舊有許多進步的空間。因此，本論文專注於提出更有智慧的機制使得多媒體廣播群播服務可以被更有效率的建置在UMTS網路上。我們考慮以下兩個非常重要的效能議題：

議題 1. 多媒體廣播群播服務之無線電資源管理機制：多媒體廣播群播服務中定義了點對點（Point-to-Point）傳輸以及點對多點（Point-to-Multipoint）的無線傳輸模式，其分別使用專用邏輯通道（Dedicated logical channel）和共用邏輯通道（Common logical channel）來傳輸多媒體廣播群播服務之資料給使用者。用共用邏輯通道時，雖可以同時服務多個使用者，但該通道必須使用足以傳送到整個涵蓋區域的傳送功率，因此會對專用邏輯通道造成嚴重干擾。所以，如何有效率地使用無線電資源來同時服務多媒體廣播群播服務以及使用專用邏輯通道之傳統電信服務使用者將是一個關鍵的議題。在此論文中，我們提出了兩種頻道分配的演算法，分別是群播資源預留(Reserved Resource for Multicasting; RRM)及群播資源不限(Unreserved Resource for Multicasting; URM)演算法。為了研究這兩個演算法的效能(包括通話未完成率以及用戶滿意度指標)，我們推導其數學分析模型，並開發模擬程式。研究數據指出不管在傳統通話服務中的通話未完成率及用戶滿意度指標中，URM都較RRM優越，但URM會稍稍減少多媒體廣播群播服務之效能。

議題 2. 多媒體廣播群播服務之檔案修復機制：當多媒體檔案以群播方式傳送給使用者的時候，由於網路擁塞以及訊號品質不良的影響，在傳輸過程中會造成資料之遺失或錯誤。為了重傳遺失或錯誤的資料，3GPP 26.346制定了三種檔案修復機制（File Repair Mechanism）。但是，這三種修復機制明顯產生額外的信令及網路流量。為了減少資料的傳輸以及解決額外信令傳遞等問題，本論文提出了新的檔案修復機制稱為Reuse Bearer Service（RBS）。我們透過數學模型分析了四種檔案修復機制並且實作模擬模型來評估這些機制之效能。我們的研究顯示，以修復所有錯誤資料所耗費之網路資源為考量時，RBS修復機制優於3GPP所定義的三種檔案修復機制。

關鍵字

頻道分配 ； 檔案修復 ； 多媒體群播廣播服務 ； 通用行動通訊服務

並列摘要

The multicasting technique (one-source-many-destination) is widely utilized for multimedia content delivery in the Internet. In the recent years, mobile telecommunication networks have been integrated with the Internet. The Third Generation Partnership Project (3GPP) working group proposed the Multimedia Broadcast Multicast Service (MBMS) for multicasting multimedia content over the Universal Mobile Telecommunications System (UMTS). The standards for the UMTS MBMS service are currently under process. It is allowed rooms to enhance the current mechanisms proposed in the UMTS MBMS specifications so that better QoS and performance for the MBMS service can be achieved in the UMTS network. This dissertation focuses on proposing more intelligent mechanisms to make the MBMS service deployed more efficiently in UMTS. We consider the following two important issues for performance enhancement for the UMTS MBMS service.

Radio Resource Management. 3GPP 23.246 defines the MBMS to deliver multicasting content over the Universal Mobile Telecommunications System (UMTS), where the common logical channel may be enabled to serve multiple MBMS users at the same time. However, the usage of the common logical channel may cause interference to the dedicated logical channels serving the traditional calls. To more efficiently utilize the radio resource to serve both traditional and MBMS calls, this dissertation proposes two channel allocation algorithms: Reserved Resource for Multicasting (RRM) and Unreserved Resource for Multicasting (URM). We develop analytic and simulation models to investigate the performance for the two algorithms, including the call incompletion probability and customers' satisfaction indication. Our study indicates that URM outperforms RRM in terms of the call incompletion probability for the traditional calls and satisfaction indication by slightly degrading the performance of MBMS calls.

File Repair Mechanism. During the MBMS content transmission, the data may be lost. Three file repair schemes were proposed in 3GPP 26.346 to retransmit the corrupted MBMS data. However, these schemes may introduce extra data traffic or signaling overheads. This dissertation proposes the Reuse Bearer Service (RBS) file repair scheme to resolve this issue. We analyze the four file repair schemes by analytical models and simulation experiments. Our study shows that the proposed RBS scheme may significantly outperform the previously proposed schemes.

並列關鍵字

Channel Allocation ； File Repair ； Multimedia Broadcast Multicast Service (MBMS) ； Universal Mobile Telecommunication System (UMTS)

參考文獻

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